U.S. patent application number 13/331892 was filed with the patent office on 2013-06-20 for metal surface and process for treating a metal surface.
This patent application is currently assigned to Apple Inc.. The applicant listed for this patent is Masashige TATEBE. Invention is credited to Masashige TATEBE.
Application Number | 20130153427 13/331892 |
Document ID | / |
Family ID | 48609036 |
Filed Date | 2013-06-20 |
United States Patent
Application |
20130153427 |
Kind Code |
A1 |
TATEBE; Masashige |
June 20, 2013 |
Metal Surface and Process for Treating a Metal Surface
Abstract
An article having a metal surface is treated to have one or more
desired effects, such as desired functional properties or a desired
cosmetic appearance. The surface is anodized to create an oxide
layer having pores therein and a metal deposition process is
performed to deposit multiple different metals within the pores. A
pretreatment act, such as degreasing, chemical etching, chemical
polishing, and desmutting can also be conducted on the surface
prior to anodization. The surface can also be dyed, sealed, and
polished.
Inventors: |
TATEBE; Masashige;
(Kakogawa, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TATEBE; Masashige |
Kakogawa |
|
JP |
|
|
Assignee: |
Apple Inc.
Cupertino
CA
|
Family ID: |
48609036 |
Appl. No.: |
13/331892 |
Filed: |
December 20, 2011 |
Current U.S.
Class: |
205/50 ; 205/121;
205/122; 205/131 |
Current CPC
Class: |
C25D 5/18 20130101; C25D
3/12 20130101; C25D 11/20 20130101; C25D 11/243 20130101; C25D
11/246 20130101; C25D 5/10 20130101 |
Class at
Publication: |
205/50 ; 205/131;
205/121; 205/122 |
International
Class: |
C25D 11/22 20060101
C25D011/22; C25D 7/04 20060101 C25D007/04; C25D 11/24 20060101
C25D011/24; C25D 11/14 20060101 C25D011/14; C25D 11/04 20060101
C25D011/04; C25D 11/16 20060101 C25D011/16 |
Claims
1. A method of treating a metal surface of an article comprising:
providing an article having a metal surface; anodizing the metal
surface to create an oxide layer on the metal surface, the oxide
layer having pores therein; and performing a metal deposition
process to deposit at least a first metal and a second metal within
the pores of the oxide layer on at least a portion of the metal
surface, wherein the first metal and the second metal are different
metals.
2. The method of claim 1, wherein the act of performing a metal
deposition process includes performing a first metal deposition
process to deposit the first metal within the pores and performing
a second metal deposition process to deposit the second metal
within the pores.
3. The method of claim 1, further comprising: dyeing the oxide
layer with a dye after performing the metal deposition process.
4. The method of claim 3, wherein the act of dyeing the oxide layer
includes depositing dye within the pores and dyeing the first metal
and second metal after the first metal and second metal are
deposited within the pores.
5. The method of claim 3, wherein a color of the dye is different
than a color of at least one of the first metal and second
metal.
6. The method of claim 3, further comprising: sealing the oxide
layer.
7. The method of claim 6, further comprising: polishing the oxide
layer after sealing the oxide layer.
8. The method of claim 1, further comprising: texturizing the metal
surface before anodizing the metal surface.
9. The method of claim 1, wherein a diameter of each of the pores
is in a range from about 0.01 to about 0.03 microns.
10. The method of claim 2, wherein the first metal is nickel and
wherein the second metal is tin.
11. The method of claim 2, wherein a color of the first metal is
different than a color of the second metal.
12. The method of claim 1, wherein the metal surface is formed of
aluminum.
13. The method of claim 1, the metal surface including a first
portion and a second portion, wherein the first metal and the
second metal are deposited within the pores of the oxide layer on
the second portion, and wherein a mask is applied to the oxide
layer on the first portion of the metal surface after the first
metal and second metal are deposited.
14. The method of claim 13, the method further comprising:
performing a metal deposition process to deposit one or more metals
within the pores of the oxide layer on the first portion of the
metal surface, and wherein a mask is applied to the oxide layer on
the second portion of the metal surface after the one or more
metals are deposited on the first portion.
15. A metal surface treated according to the method of claim 1.
16. The method of claim 1, wherein the article is an electronic
device housing.
17. An article of manufacture, comprising: a metal surface
including an oxide layer having pores that are at least partially
filled with a first deposited metal and a second deposited
metal.
18. The article of claim 17, wherein the pores that are partially
filled with the first and second deposited metals are sealed.
19. The article of claim 17, wherein the first metal is a different
metal than the second metal.
20. The article of claim 17, wherein a color of the first metal is
different than a color of the second metal.
21. A method of treating an aluminum surface of a component for an
electronic device comprising: providing a component for an
electronic device having an aluminum surface; anodizing the surface
in a sulfuric acid bath to create an oxide layer having pores
therein; drying the oxide layer surface; performing a metal
deposition process to deposit nickel and tin at the bottom of the
pores; dyeing both the oxide layer and the deposited materials; and
sealing the nickel and the tin within the pores.
22. The method of claim 21, wherein the act of performing a metal
deposition process to deposit nickel and tin within the pores
includes a first act of depositing one of nickel and tin within the
pores followed by a second act of depositing the other of tin and
nickel within the pores.
23. The method of claim 21, further comprising: polishing the oxide
layer after sealing the oxide layer.
24. The method of claim 21, wherein a color of the dye is different
than a color of at least one of the deposited first and second
metals.
25. The method of claim 21, wherein the component for an electronic
device is a housing for a handheld electronic device.
Description
BACKGROUND
[0001] 1. Field
[0002] The present invention relates to treatments for a surface of
an article and an article with such a treated surface.
[0003] 2. Background
[0004] Many products in the commercial and consumer industries have
metal surfaces. Such metal surfaces can be treated by any number of
processes to create a desired effect, either functional, cosmetic,
or both. One example of such a surface treatment is anodization.
Anodizing a metal surface converts a portion of the metal surface
into a metal oxide, thereby creating, a metal oxide layer. Anodized
metal surfaces provide increased corrosion resistance and wear
resistance. Anodized metal surfaces can be used to obtain a desired
cosmetic effect. For example, pores in the oxide layer formed
during anodization can be filled with metal or dyes to impart a
desired color to the surface.
[0005] The cosmetic effect of metal surface treatments can be of
great importance. In consumer product industries, such as the
electronics industry, visual aesthetics can be a deciding factor in
a consumer's decision to purchase one product over another.
Accordingly, there is a continuing need for new surface treatments
or combinations of surface treatments for metal surfaces to create
products with new and different visual appearances or cosmetic
effects.
BRIEF SUMMARY
[0006] In broad terms, a metal surface can be treated using a metal
deposition process to create a desired effect. A method of treating
a metal surface of an article can include anodizing the surface to
create an oxide layer having pores therein, and performing a metal
deposition process to deposit multiple different metals within the
pores. The deposited metals can impart a color to the oxide layer.
The oxide layer and/or the deposited metals can be dyed. The color
of the dye can be the same or different than the color of the
deposited metals.
[0007] The article can be an article of manufacture having a metal
surface that has been treated so that the pores of the oxide layer
are partially filled with a first metal and a second metal via the
metal deposition process.
[0008] The metal surface can be an aluminum surface and the article
can be a handheld device. The surface can be anodized using a
sulfuric acid bath to create an oxide layer having pores. The oxide
layer surface can be dried, and a metal deposition process can be
performed to deposit metal such as nickel and tin within the pores.
The oxide layer and deposited materials can be dyed, and the nickel
and tin can be sealed within the pores.
[0009] Additional features of the invention will be set forth in
the description that follows, and in part will be apparent from the
description, or can be learned by practice of the invention. Both
the foregoing general description and the following detailed
description are exemplary and explanatory and are intended to
provide further explanation of the embodiments as claimed.
BRIEF DESCRIPTION OF THE FIGURES
[0010] The accompanying figures, which are incorporated herein,
form part of the specification and illustrate exemplary embodiments
of the present invention. Together with the description, the
figures further serve to explain the principles of, and to enable a
person skilled in the relevant art(s) to make and use the exemplary
embodiments described herein.
[0011] FIG. 1 is a flowchart of a surface treatment process in
accordance with one embodiment of the present application.
[0012] FIG. 2 illustrates an enlarged perspective view of a portion
of a surface that has been treated in accordance with one
embodiment of the present application.
[0013] FIG. 3 illustrates a cross-sectional view of a portion of
the surface of FIG. 2 following a metal deposition process in
accordance with one embodiment of the present application.
[0014] FIG. 4 is a flowchart of a surface treatment process in
accordance with one embodiment of the present application.
[0015] FIG. 5 is a cross-sectional view of a portion of the surface
of FIG. 2 following a metal deposition process and a dyeing process
in accordance with one embodiment of the present application.
[0016] FIG. 6 illustrates a plan view of a portion of the surface
of FIG. 2 treated in accordance with one embodiment of the present
application.
[0017] FIG. 7 is a flowchart of a process of surface treatment in
accordance with one embodiment of the present application.
[0018] FIG. 8 is a flowchart of a process of surface treatment in
accordance with one embodiment of the present application.
[0019] FIG. 9 is a flowchart of a process of surface treatment in
accordance with one embodiment of the present application.
[0020] FIG. 10 illustrates a plan view of a portion of the surface
of FIG. 2 treated in accordance with one embodiment of the present
application.
DETAILED DESCRIPTION
[0021] The following detailed description refers to the
accompanying figures, which illustrate exemplary embodiments. Other
embodiments are possible. Modifications can be made to the
exemplary embodiments described herein without departing from the
spirit and scope of the present invention. Therefore, the following
detailed description is not meant to be limiting. The operation and
behavior of the embodiments presented are described with the
understanding that modifications and variations can be within the
scope of the present invention.
[0022] FIG. 1 is a high-level flowchart of an exemplary surface
treatment process 8. Process 8 includes an act 10 of providing an
article having a metal surface, such as a metal part having a metal
surface. This process can be applied to a broad range of metal
parts including, but not limited to, household appliances and
cookware, such as pots and pans; automotive parts; athletic
equipment, such as bikes; and parts for use with electronic
components, such as housings or other components for laptop
computers, housings or other components for handheld electronic
devices, such as tablet computers, media players, and phones, and
housings or other components for other electronic devices, such as
desktop computers. In some embodiments, the method can be
implemented on a housing for a media player or laptop computer
manufactured by Apple Inc. of Cupertino, Calif.
[0023] Suitable metal surfaces include aluminum, titanium,
tantalum, magnesium, niobium, stainless steel, and the like. A
metal part including a metal surface can be formed using a variety
of techniques, and can come in a variety of shapes, forms and
materials. Examples of techniques include providing the metal part
as a preformed sheet or extruding the metal part so that it is
formed in a desired shape. In one example, the metal part can be
extruded so that the metal part is formed in a desired shape.
Extrusion can be a process for producing a desired shape in a
continuous manner of indeterminate length so that the material can
be subsequently cut to a desired length. In one embodiment, the
metal part can be shape cast via any suitable casting process, such
as die casting and permanent mold casting processes, among others.
In one embodiment, the metal part can be formed from aluminum, such
as extruded 6063 grade aluminum. In some embodiments, the metal
part is made of an aluminum-nickel or aluminum-nickel-manganese
casting alloy. The choice of any materials described herein can be
further informed by mechanical properties, temperature sensitivity,
or any other factor apparent to a person having ordinary skill in
the art. In some embodiments, the metal part can include a plastic
substrate with a surface layer of metal joined thereto.
[0024] Process 8 additionally includes an act 12 of performing an
anodization process on the metal surface. Anodizing a metal surface
converts a portion of the metal surface into a metal oxide, thereby
creating a metal oxide layer. Anodized metal surfaces can provide
increased corrosion resistance and wear resistance. An exemplary
anodization process includes placing the metal surface in an
electrolytic bath having a temperature in a range from about 18 to
about 22 degrees Celsius. Hard anodization can be accomplished by
placing the metal surface in an electrolytic bath having a
temperature in a range from about 0 to about 5 degrees Celsius.
[0025] In one embodiment, anodizing act 12 can create a transparent
effect to the metal surface. In this embodiment, the metal surface
can be placed in an electrolytic bath that has been optimized to
increase the transparent effect of the oxide layer. The
electrolytic bath can include sulfuric acid (H.sub.2SO.sub.4) in a
concentration having a range from about 150 to about 210 g/l, from
about 160 and to about 200 g/l, from about 170 to about 190 g/l, or
about 180 g/l. The electrolytic bath can also include metal ions
that are the same metal as the metal surface. For example, the
metal surface can be formed of aluminum, and the electrolytic bath
can include aluminum ions, in a concentration of about less than 15
g/l or in a range from about 4 to about 10 g/l, from about 5 to
about 9 g/l, or from about 6 to about 8 g/l, or can be about 7 g/l.
A current is passed through the solution to anodize the article.
Anodization can occur at a current density in a range from about
1.0 to about 2.0 amperes per square decimeter. Anodization can have
a duration in a range from about 30 minutes to about 60 minutes, or
from about 35 to about 55 minutes, or from about 40 to about 50
minutes, or can be about 45 minutes. The thickness of the oxide
layer can be controlled in part by the duration of the anodization
process.
[0026] In order to achieve an oxide layer with a desired
transparency, the thickness of the oxide layer can range from about
10 microns to about 20 microns, or from about 11 to about 19
microns, or from about 12 microns to about 18 microns, or from
about 13 to about 17 microns, or from about 14 microns to about 16
microns, or about 15 microns. Pores are formed during the
anodization process and in one embodiment are spaced approximately
10 microns apart. The diameter of each of the pores can range from
0.005 to about 0.05 microns, or from 0.01 to about 0.03 microns.
The above dimensions are not intended to be limiting.
[0027] Process 8 further includes an act 14 of depositing one or
more metals within the pores of the oxide layer formed during
anodization to impart a desired color below the surface and into
the pores of the oxide layer. In one embodiment, following
anodization the article is immersed in an electrolyte bath
including an inorganic metal salt in solution or a combination of
two or more different inorganic metal salts in solution. For
example, the metal salts can include salts of nickel, tin, cobalt,
copper, or any other suitable metals. In one embodiment, an
electrolyte bath solution can be used that contains a package
chemical such as "Top Alcolord ED" from Okuno Chemical Industries
Co., Ltd. of Osaka, Japan, at a concentration of about 300 mL/L,
nickel-sulfide at a concentration of about 50 g/L, boric acid at a
concentration of about 30 g/L, and a package chemical such as "Top
Alcolord ED Special Additive" from Okuno Chemical Industries Co.,
Ltd. of Osaka, Japan, at a concentration of about 8 g/L. The
package chemicals can be an additive, which, for example, can
stabilize the reaction within the electrolyte bath. The solution
can be maintained at a temperature of about 25 degrees Celsius, for
example.
[0028] An alternating or direct current is then applied to the
electrolyte bath so that the metal ions of the salt come out of the
solution and deposit as a metal in the base of the pores of the
oxide layer. The voltage, frequency, and/or other characteristics
of the current can be changed during act 14 in order to achieve a
desired effect. For example, in one embodiment, an alternating
current at a frequency of about 60 Hz and voltage of about 4V can
be applied for about 30 seconds. The voltage of the current can
then be increased to about 6V for about 30 seconds. Following this,
the voltage of the current can then be increased to about 11V for a
time ranging from about 30 seconds to about 15 minutes.
[0029] In some embodiments, multiple different metals (via
different metal ions in the solution) are deposited within the
pores of the oxide layer. For example, in one embodiment, nickel
and tin are deposited within the pores of the oxide layer. The
multiple deposited metals can be the same or different colors and
can be the same or different colors from the metal surface or the
oxide layer. The combination of metal colors can result in a
surface having a desired color. In one embodiment, the deposited
metals fill less than half the volume of each pore. The metal
deposition act 14 can include performing a first metal deposition
process to deposit a first metal within the pores of the oxide
layer and performing a second metal deposition process to deposit a
second metal within the pores of the oxide layer. The first and
second metals can be different metals, such as nickel and tin for
example.
[0030] For example, the electrolyte bath solution can contain
concentrated sulfuric acid (H.sub.2SO.sub.4) at a concentration of
about 15 g/L, tin sulfate (SnSO.sub.4) at a concentration of about
8 g/L, nickel sulfate (NiSO.sub.4) at a concentration of about 30
g/L, and tartaric acid (C.sub.4H.sub.6O.sub.6) at a concentration
of about 15 g/L. The solution can be maintained at approximately
room temperature (e.g., about 23 degrees Celsius), for example.
[0031] In one embodiment, an alternating current at a voltage of
about 4V can be applied for about 30 seconds. The voltage of the
current can then be increased to about 6V for about 30 seconds. The
voltage of the current can then be increased to a voltage that can
range from between about 10V to about 11V over the course of about
30 seconds. The current can then be maintained at a voltage that
can range from about 10V to about 11V for a time ranging from about
5 minutes to about 10 minutes.
[0032] FIG. 2 illustrates an enlarged view of a portion of a
surface 16 treated in accordance with one embodiment of the present
invention. Surface 16 includes an oxide layer 18 formed over a
metal surface 20. Anodic cells 24 are formed within oxide layer 18
and include a pore 22 formed within each cell during anodization
act 12 described above.
[0033] FIG. 3 illustrates a cross-sectional view of surface 16
following metal deposition act 14. As described above, surface 16
includes oxide layer 18 formed over metal surface 20 with multiple
pores 22 formed within oxide layer 18. Following metal deposition
act 14, one or more metals 26 are deposited at the bottom of each
pore 22. For example, the embodiment of FIG. 3 illustrates two
metals 26a and 26b deposited within each pore 22.
[0034] FIG. 4 is a high-level flowchart of an exemplary surface
treatment process 28. Process 28 includes the acts described above
of providing an article having a metal surface 20 (act 10),
anodizing metal surface 20 to create oxide layer 18 having pores 22
(act 12), and depositing one or more metals 26 (26a, 26b) within
pores 22 of oxide layer 18 (act 14). Process 28 further includes an
act 30 of dyeing oxide layer 18.
[0035] By way of example, act 30 of dyeing oxide layer 18 can
include dipping or immersing oxide layer 18 or the entire article
in a dye solution in order to impart a rich color to oxide layer
18. As described above, oxide layer 18 is porous in nature, which
allows it to absorb a dye into pores 22. In some embodiments, the
particle size of the dye molecule is from about 5 nm to about 60
nm, or from about 15 nm to about 30 nm. The act of dyeing oxide
layer 18 can include dyeing oxide layer 18 and/or deposited metals
26 within pores 22. In one embodiment, an organic dye is used to
dye oxide layer 18. If suitable, an inorganic dye can be used to
dye oxide layer 18. Any suitable combination of organic and
inorganic dyes can be used. The color of the dye can be the same or
different than the color of metal(s) 26 deposited within pores 22
of oxide layer 18. When at least two metals are deposited, the
color of the dye can be different from either one or both of the
metals.
[0036] In one embodiment, the dye solution can be maintained at a
temperature in a range from about 50 to about 55 degrees Celsius
and can contain a stabilizer to control the pH of the dye solution.
A variety of colors can be achieved depending upon the particular
dye composition, dye concentration, and/or duration of dyeing. A
variety of colors for oxide layer 18 can be achieved by varying the
dye composition, the concentration of the dye and the duration of
dyeing based on visualization and/or experimentation. Color control
can be achieved by measuring oxide layer 18 with a
spectrophotometer and comparing the value against an established
standard.
[0037] FIG. 5 illustrates a cross-sectional view of surface 16
following metal deposition act 14 and dyeing act 30. As described
above, surface 16 includes oxide layer 18 formed over metal surface
20. Multiple pores 22 are formed within oxide layer 18. Following
metal deposition act 14, one or more metals 26 (26a, 26b) are
deposited at the bottom of each pore 22. Following dyeing act 30,
dye 32 is also deposited within pore 22. FIG. 6 illustrates a plan
view of a portion of surface 16 treated in accordance with the
process described herein in which a particular appearance (e.g.,
color) has been imparted to surface 16 via deposited metals 22
and/or dye 32.
[0038] FIG. 7 is a high-level flowchart of an exemplary process 34
of surface treatment. Process 34 includes the acts as described
above of providing an article having a metal surface 20 (act 10),
anodizing metal surface 20 to create an oxide layer 18 having pores
22 (act 12) and depositing one or more metals 26 within pores 22 of
oxide layer 18 (act 14). Process 34 further includes an act 36 of
sealing oxide layer 18.
[0039] By way of example, act 36 of sealing oxide layer 18 can
include immersing a metal surface in a sealing solution to seal
pores 22. The sealing process can include placing oxide layer 18 in
a solution for a sufficient amount of time to create a sealant
layer that seals pores 22. The sealing solution can include, but is
not limited to, nickel acetate. The sealing solution can be kept at
a temperature in a range from about 90 to about 95 degrees Celsius.
Oxide layer 18 can be immersed in the solution for a period of at
least 15 minutes. In some embodiments, the sealing is performed
using hot water or steam to convert a portion of oxide layer 18
into its hydrated form. This conversion allows oxide layer 18 to
swell, thus reducing the size of pores 22.
[0040] FIG. 8 is a high-level flowchart of an exemplary process 38
of surface treatment.
[0041] Process 38 includes the acts as described above of providing
an article having metal surface 20 (act 10), anodizing metal
surface 20 to create oxide layer 18 having pores 22 (act 12) and
depositing one or more metals 26 within pores 22 of oxide layer 18
(act 14). Process 38 further includes an act 40 of texturizing
metal surface 20 before anodization (act 12).
[0042] Act 40 of texturizing metal surface 20 includes performing a
texturizing treatment on metal surface 20 to create a textured
pattern across the surface. This act can result in one or more
decorative, structural, functional, or other effects on metal
surface 20. In one such process, surface 20 can be texturized to
roughen the surface, shape the surface, remove surface
contaminants, or other effects. For example, the texturizing act
can produce a desired tactile effect, reduce the appearance of
minor surface defects, and/or reduce the appearance of fingerprints
or smudges. In addition, the texturizing act can be used to create
a series of small peaks and valleys. These peaks and valleys can
impart a sparkling effect to the surface, which can in some
instances make the surface appear brighter.
[0043] This texturizing process can be accomplished via one or more
mechanical processes such as by machining, brushing, or abrasive
blasting. Abrasive blasting, for example, involves forcibly
propelling a stream of abrasive material, such as beads, sand,
and/or glass, against the surface. Alternatively, the surface can
be texturized through a chemical process, such as chemical etching.
This process can involve the use of an etching solution, such as an
alkaline etching solution.
[0044] The alkaline etching solution can be a sodium hydroxide
(NaOH) solution. The concentration of the NaOH solution can range
from about 50 to about 60 g/l, from about 51 to about 59 g/l, from
about 52 to about 58 g/l, from about 53 to about 57 g/l, or from
about 54 to about 56 g/l, or can be about 55 g/l. The NaOH solution
can have a temperature of about 50 degrees Celsius. Surface 20 can
be exposed to the NaOH solution for a time period that can range
from about 5 to about 30 seconds, from about 10 to about 25
seconds, or from about 15 to about 20 seconds. These parameters are
merely exemplary and can be varied. For example, other suitable
etching solutions can be used, including, but not limited to
ammonium bifluoride (NH.sub.4F.sub.2).
[0045] FIG. 9 is a high-level flowchart of an exemplary process 42
of surface treatment. Process 42 includes the acts as described
above of providing an article having metal surface 20 (act 10),
anodizing metal surface 20 to create oxide layer 18 having pores 22
(act 12), depositing one or more metals 26 within pores 22 of oxide
layer 18 (act 14), dyeing oxide layer 18 (act 30), and sealing
oxide layer 18 (act 36). Process 42 further includes an act 44 of
polishing oxide layer 18. Act 44 can be conducted after sealing
oxide layer 18 (act 36).
[0046] Act 44 of polishing oxide layer 18 can be accomplished
through any suitable polishing methods, such as buffing or
tumbling. This act can be performed manually or with machine
assistance. In one embodiment, buffing can be accomplished by
polishing oxide layer 18 using a work wheel having an abrasive
surface. In one embodiment, oxide layer 18 can be polished via
tumbling, which involves placing the article in a tumbling barrel
filled with a media and then rotating the barrel with the object
inside it. Polishing act 44 can impart a smooth, glassy appearance
to oxide layer 18. For example, polishing act 44 can include
tumbling the article in a barrel for about 2 hours at a rotational
speed of about 140 RPM. In some embodiments, the volume of the
barrel can be about 60% filled, and the media can be crushed walnut
shells mixed with a cutting media suspended in a lubricant, such as
a cream.
[0047] In some embodiments, polishing act 44 includes an automated
buffing process, which can be a multi-stage process. An exemplary
multi-stage process for automated buffing can include four stages.
In a first stage, oxide layer 18 can be buffed for about 17 seconds
with a pleated sisal wheel coated with an oil having coarse
aluminum oxide particles suspended therein. In a second stage,
oxide layer 18 can be buffed in a cross direction from the buffing
of the first stage for about 17 seconds with a pleated sisal wheel
coated with an oil having coarse aluminum oxide particles suspended
therein. In a third stage, oxide layer 18 can be buffed for about
17 seconds with an un-reinforced cotton wheel coated with an oil
having finer aluminum oxide particles suspended therein than the
coarse aluminum oxide particles utilized in the first and second
stages. In a fourth stage, oxide layer 18 can be buffed for about
17 seconds with a flannel wheel coated with an oil having finer
aluminum oxide particles suspended therein than the coarse aluminum
oxide particles utilized in the first through third stages. The
type of abrasive particles, the size of the abrasive particles, the
duration of the stage, and the material of the wheel described
above for each stage, as well as the number of stages, are merely
exemplary and can be varied.
[0048] Polishing act 44 can additionally or alternatively include
the use of a chemical polishing solution. The chemical polishing
solution can be an acidic solution. Acids that can be included in
the solution include, but are not limited to, phosphoric acid
(H.sub.3PO.sub.4), nitric acid (HNO.sub.3), sulfuric acid
(H.sub.2SO.sub.4), and combinations thereof. The acid can be
phosphoric acid, a combination of phosphoric acid and nitric acid,
a combination of phosphoric acid and sulfuric acid, or a
combination of phosphoric acid, nitric acid and sulfuric acid.
Other additives for the chemical polishing solution can include
copper sulfate (CuSO.sub.4) and water. In one embodiment, a
solution of 85% phosphoric acid is maintained at a temperature of
about 95 degrees Celsius. The processing time of the chemical
polishing act can be adjusted depending upon a desired target gloss
value. In one embodiment, the processing time can be in a range
from about 40 to about 60 seconds. In addition, act 44 of polishing
can be accomplished utilizing other methods that would result in
polishing oxide layer 18 to increase the gloss of oxide layer
18.
[0049] In some embodiments, polishing act 44 results in a high
quality surface with no orange peel, no waviness, and no defects.
For example, all die lines, stamping marks, drawing marks, shock
lines, cutter marks, roughness, waviness, and/or oil and grease can
be removed from oxide layer 18 via polishing act 44. Similar
treatment can be performed before the anodization act 12 described
above.
[0050] Additionally, any of the above methods can include one or
more further treatments on the metal surface 20 or oxide layer 18,
such as rinsing, degreasing, desmutting, dyeing, sealing,
polishing, texturizing, brightening, or anodization acts.
[0051] In some embodiments, a first portion of metal surface 20 or
oxide layer 18 can be treated differently than a second portion of
metal surface 20 or oxide layer 18 in order to create different
patterns and/or visual effects. For example, in one embodiment, the
first portion can be treated using the texturizing process
described herein, and the second portion may not be subject to a
texturizing act. In another embodiment, the first surface portion
and second surface portions can be treated by different techniques.
For example, the first surface portion can be subjected to abrasive
blasting or chemical etching and the second surface portion can be
subjected to another texturizing process described herein.
[0052] In addition, the two surface portions can be treated to have
different degrees of scratch or abrasion resistance. For example,
one technique can include standard anodization on one portion of
the surface and the other technique can include hard anodization on
another portion of the surface, or one technique can polish to a
different surface roughness one portion of the surface compared to
another technique performed on another portion of the surface. The
different patterns or visual effects on surface 16 that are created
can include, but are not limited to, stripes, dots, or the shape of
a logo. In one embodiment, surface 16 includes a logo, wherein the
first portion of surface 16 includes the logo and the second
portion of surface 16 does not contain the logo. In other
embodiments, the difference in techniques can create the appearance
of a logo or label, such that a separate logo or label does not
need to be applied to surface 16. For example, this can be
accomplished through the use of a mask during one or more stages of
the process. In one embodiment, a mask is applied to a first
portion of the surface while a second portion of the surface
undergoes one treatment process. The mask is then removed. A mask
can then be applied to the second portion of the surface while the
first portion of the surface undergoes a different treatment
process.
[0053] In one embodiment, a first metal is deposited within the
pores of the oxide layer on the first portion of the article, and a
second metal is deposited within pores of the oxide layer on the
second portion of the article. In one embodiment, first and second
metals are deposited within the pores of the oxide layer on the
first portion of the article, and a third metal is deposited within
pores of the oxide layer on the second portion of the article. In
another embodiment, first and second metals are deposited within
pores of the oxide layer on the first portion of the article, and
third and fourth metals are deposited within pores of the oxide
layer on the second portion of the article. Each of the first,
second, third, and fourth metals are different from each other. In
any of these embodiments, the oxide layer on the first portion can
be masked while the metal(s) are deposited within the oxide layer
pores of the second portion. The oxide layer of the second portion
can be masked while the metal(s) are deposited within the oxide
layer pores of the first portion. For example, FIG. 10 shows a plan
view of a portion of surface 16 having a first portion 16a with a
first appearance (e.g., one color) and a second portion 16b with a
second appearance (e.g., another color).
[0054] It is noted that the acts discussed above, for example the
acts illustrated in the flowcharts of FIGS. 1, 4, and 7-9 are for
illustrative purposes and are merely exemplary. Not every act need
be performed and additional acts can be included as would be
apparent to one of ordinary skill in the art to create a surface 16
having a desired effect. The acts can be reordered as desired. For
example, act 44 of polishing the metal surface can be performed
before or after the texturizing act 40 as well as before or after
the anodizing act 12.
Example 1
[0055] In one prophetic example, a surface treatment process in
accordance with one embodiment of the present application is
applied to an aluminum housing for a portable media player. The
housing is first rinsed to remove any debris. The housing is then
placed in a chemical etching solution containing NaOH for
approximately 20 seconds. After this process, the housing is
removed from the solution and rinsed with clean water.
[0056] The housing is then anodized to create an oxide layer. The
housing is placed in an electrolytic bath having a temperature of
about 20 degrees Celsius. A current having a current density of
about 1.5 amperes per square decimeter is passed between a cathode
in the solution and the housing to create a build-up of aluminum
oxide on the housing. This process is performed for approximately
40 minutes and can result in an oxide layer being formed on the
surface of the housing. After this process, the housing is removed
from the bath and rinsed with clean water.
[0057] The housing is then immersed in an electrolyte bath
including nickel salt in solution. The electrolyte bath solution
contains "Top Alcolord ED" from Okuno Chemical Industries Co., Ltd.
of Osaka, Japan, at a concentration of about 300 mL/L,
nickel-sulfide at a concentration of about 50 g/L, boric acid at a
concentration of about 30 g/L, and "Top Alcolord ED Special
Additive" from Okuno Chemical Industries Co., Ltd. of Osaka, Japan,
at a concentration of about 8 g/L. The solution can be maintained,
for example, at a temperature of about 25 degrees Celsius.
[0058] After the housing is immersed in the electrolyte bath, an
alternating current at a frequency of about 60 Hz and voltage of
about 4V is applied for about 30 seconds. The voltage of the
current is then increased to about 6V for about 30 seconds.
Following this, the voltage of the current is then increased to
about 11V for about 5 minutes. After this process, the housing is
then removed from the bath, rinsed with clean water, and dyed by
dipping the article in an organic dye solution.
[0059] The pores of the housing are then sealed by placing the
article in a solution of nickel acetate for about 15 minutes. After
the pores of the housing are sealed, the housing is chemically
polished by placing the article in a solution of 85% phosphoric
acid for about 40 seconds. The housing is then rinsed with clean
water and buffed for about 20 seconds with a pleated sisal wheel
coated with an oil having coarse aluminum oxide particles suspended
therein.
Example 2
[0060] In another prophetic example, a surface treatment process in
accordance with one embodiment of the present application is
applied to an aluminum housing for a laptop computer. The housing
is first rinsed to remove any debris. A mask in the shape of a logo
is applied to a portion of the housing to create an exposed portion
of the housing and an unexposed portion of the housing. The housing
is then sandblasted to create a desired texture on the exposed
portion of the housing. After this process, the housing is removed
from the solution, the mask is removed, and the housing is rinsed
with clean water.
[0061] The housing is then anodized to create an oxide layer. The
housing is placed in an electrolytic bath having a temperature of
about 20 degrees Celsius. A current having a current density of
about 1.5 amperes per square decimeter is passed between a cathode
in the solution and the article to create a build-up of aluminum
oxide on the article. This process is performed for approximately
40 minutes and results in an oxide layer being formed on the
surface of the housing. After this process, the housing is removed
from the bath and rinsed with clean water.
[0062] The housing is then immersed in an electrolyte bath
containing concentrated sulfuric acid (98% H.sub.2SO.sub.4) at a
concentration of about 15 g/L, tin sulfate (SnSO.sub.4) at a
concentration of about 8 g/L, nickel sulfate (NiSO.sub.4) at a
concentration of about 30 g/L, and tartaric acid
(C.sub.4H.sub.6O.sub.6) at a concentration of about 15 g/L. The
solution is maintained at approximately 23 degrees Celsius.
[0063] After the housing is immersed in the electrolyte bath, an
alternating current at a voltage of about 4V is applied for about
30 seconds. The voltage of the current is then increased to about
6V for about 30 seconds. The voltage of the current is then
increased to about 11V over the course of about 30 seconds. The
voltage is then maintained at about 11V for about 8 minutes. After
this process, the housing is then removed from the bath and rinsed
with clean water. The pores of the housing are then sealed by
placing the article in a solution of nickel acetate for about 15
minutes.
[0064] The above processes can provide a metal surface having a
desired effect, such as desired functional properties or a desired
cosmetic appearance (e.g., a desired color). For example, in some
embodiments, the processes can achieve corrosion resistance as well
as a uniform color of the surface that does not flake or scratch
through. The processes described herein also allow for a wide
variation of visual appearances and cosmetic effects to be imparted
to a metal surface.
[0065] The foregoing description of the specific embodiments will
so fully reveal the general nature of the invention that others
can, by applying knowledge within the skill of the art, readily
modify and/or adapt for various applications such specific
embodiments, without undue experimentation, without departing from
the general concept of the present invention. Therefore, such
adaptations and modifications are intended to be within the meaning
and range of equivalents of the disclosed embodiments, based on the
teaching and guidance presented herein. It is to be understood that
the phraseology or terminology herein is for the purpose of
description and not of limitation, such that the terminology or
phraseology of the present specification is to be interpreted by
the skilled artisan in light of the teachings and guidance.
[0066] In addition, the breadth and scope of the present invention
should not be limited by any of the above-described exemplary
embodiments, but should be defined only in accordance with the
following claims and their equivalents.
* * * * *